var SIZE_ARTICLE = 12;
function changeFontSize(size)
{
    var newTextSize = SIZE_ARTICLE + size;
    if( (newTextSize >= 12) && (newTextSize <= 18) )
    {
        var Elmt = document.getElementById("article");
        Elmt.className = "article"+newTextSize;
        SIZE_ARTICLE = newTextSize;
    }
    if(SIZE_ARTICLE > 12) {
        document.getElementById("taille_txt_min").src="/blocks/sp.fr/img/a-on.png";
    } else {
        document.getElementById("taille_txt_min").src="/blocks/sp.fr/img/a-off.png";
    }
    
    if(SIZE_ARTICLE < 18) {
        document.getElementById("taille_txt_max").src="/blocks/sp.fr/img/a+on.png";
    } else {
        document.getElementById("taille_txt_max").src="/blocks/sp.fr/img/a+off.png";
    }
}